This both agree and disagree with you on this . For the most part it is true but I do know exceptions. When I was younger we proved out the following:
I agree with what you posted, but fact is that cops will stop based on vehicle profiling because such profiling can be an effective screening tool. What proportion of sportbikes are running around without insurance? Would you expect the same proportion among heavy touring bikes? Same goes with targeted sweeps for vehicle safety inspections - the beaters will get pulled over long before the shiny newer cars because that is where you're more likely to find safety deficiencies.
In the end though, your own experience tells the story. With or without sticker, you were on your way fairly quickly and painlessly. The cop didn't "manufacture" a charge (valid or otherwise) even though he easily could have on each occasion. I think this reflects the mainstream experience among drivers stopped other than those stopped while hooligan-driving or hooligan-riding.